1. Field of the Invention
This invention generally relates to siloxane urethane (meth)acrylate compounds and compositions containing same, useful as adhesives and coatings which are curable under elevated temperature and/or actinic radiation exposure conditions, and to methods of making and using such compounds and compositions.
2. Description of the Related Art
U.S. Pat. No. 4,130,708 to C. B. Friedlander, et al discloses radiation curable monomeric or oligomeric compounds, formed as reaction products of a siloxy-containing polycarbinol, a polyisocyanate, and a polyfunctional compound, which form protective films having good slip properties, fast cure and high abrasion resistance on paper and paperboard stock. The polyfunctional compound has at least one functional group, e.g., hydroxy, which is reactive with an isocyanato group of the polyisocyanate and after reaction therewith provides at least one ethylenic functional group, e.g., acrylyl, in the reaction product. At least one urethane moiety is formed by the polyisocyanate at a reactive carbinol group of the polycarbinol.
The polycarbinol contains at least two hydroxyl groups per molecule, positioned terminally or along the siloxane backbone, with preferred polycarbinol compounds having average molecular weights of about 800 to about 6,000. Among the various polycarbinol compounds disclosed are polydimethylsiloxane having terminal hydroxy groups wherein the carbyl portion of the carbinol group attached to the silicon atom is alkylene, e.g., ethylene, 1,2-propylene, 1,4-butylene, and the like (column 4, lines 40-41).
To form such reaction products, the Friedlander et al patent discloses at column 5, lines 21-25 to react the polycarbinol and polyisocyanate to form a siloxane-urethane intermediate having at least one terminal isocyanato group, followed by reaction of the intermediate with the polyfunctional, e.g., hydroxyacrylate, compound. The polyfunctional compound may be utilized in excess in the reaction, as a reactive diluent for the reaction product. It is disclosed to use the reaction product as an additive to coating compositions containing other radiation polymerizable components, such as polyesters, polyurethanes and polyamides.
At column 7, lines 44-64 of the patent, various substrates utilizable with such compositions are disclosed, as including polymeric substrates, e.g., polyesters, polyamides, cured phenolic resins, cured aminoplasts, acrylics, polyurethanes and rubber; vinyl-containing polymerizable compositions, e.g., vinyl chloride, vinyl acetate, vinyl fluoride, vinylidene chloride and "copolymerizable combinations of [such] vinyl-containing compounds with ethylene or propylene" (column 7, lines 60-64); inorganic substrates such as glass, quartz and ceramic materials; and metallic substrates including iron, steel and aluminum.
Acrylated urethane silicone compounds formed as reaction products of a silicone carbinol, a polyisocyanate and a hydroxy-functional acrylate are also disclosed in U.S. Pat. No. 4,369,300 and Canadian Pat. No. 1,134,984 to R. G. Carter, et al. The Canadian patent discloses (at page 4) that the silicone carbinol may be of the polydimethylsiloxy type, containing from 1-1,000 siloxy repeating units in its backbone and having terminal R'OH groups wherein R' is C.sub.1 -C.sub.16 alkylene.
L. P. Harasta, et al in an article entitled "Radiation-Curable Overcoat Compositions and Toner-Imaged Elements Containing Same", RESEARCH DISCLOSURE, May, 1983, pages 188-190 disclose curable coating compositions comprising (a) either (i) a mixture of a siloxy-containing polycarbinol and an acrylated urethane or (ii) a siloxy-containing acrylated urethane, (b) a multifunctional acrylate, and optionally (c) a free radical photoinitiator. The multi-functional acrylate in such composition may be present in an amount of about 20-95%, based on total composition weight, and is an acrylic monomer comprising at least two acrylic ester groups.
Australian Patent Application No. 20051/83 of K. F. Mueller, et al discloses polysiloxane copolymer compositions useful for making contact lenses, comprising the crosslinked copolymerization product of (a) about 8-70% by weight of a linear or branched polysiloxane macromer containing at least two terminal or pendant polymerizable olefinic groups per each 5,000 molecular weight unit of polysiloxane, attached to the polysiloxane through at least two urethane linkages, and (b) about 30-92% by weight mono-olefinic and/or diolefinic monomers, 85-100% by weight of which are water-insoluble. The application discloses to form the polysiloxane macromer by reaction of a siloxane having terminal hydroxyalkyl groups, wherein the alkyl moiety is C.sub.2 -C.sub.6 alkylene, with a di- or tri-isocyanate to form a prepolymer (polysiloxane polyisocyanate) intermediate, which is end capped with an active hydrogen monomer such as acrylates or methacrylates. Among the disclosed monomers useful for copolymerization with the (meth)acrylate-capped silicone urethane are methyl methacrylate and isobornyl methacrylate, preferably in admixture with 1-25 weight percent of a short chain crosslinking agent, e.g., neopentylene glycol diacrylate, ethylene glycol dimethacrylate, or isophorone diisocyanate/2-hydroxyethyl methacrylate reaction products.
PCT Patent Application No. WO84/00424 of R. E. Ansel, et al discloses a radiation-curable coating for optical fibers, comprising an organic polysiloxane with 2-6 monoethylenically unsaturated side chains each containing an acrylic or methacrylic group, and with about one such side chain for every 500-5,000 units of molecular weight. Such polysiloxanes are formed from corresponding compounds whose side chains include saturated aliphatic hydrocarbon groups containing two to four carbon atoms, e.g., 2-hydroxypropyl, or polyoxyalkylene ethers in which the alkylene group contains from two to four carbon atoms, e.g., hydroxy polyoxypropyl, such hydroxyl functional groups being reacted with a (meth)acrylate carrying a single isocyanate group. The application at page 7, lines 25-33 discloses to add monoethylenic monomers, such as mono- or poly-acrylates to the polysiloxane reaction product to adjust the viscosity of the coating composition.
UK Patent Application No. 2,110,702 describes radiation-curable oligomeric compositions useful for making optical elements and comprising polysiloxane, diurethane and methacrylate moieties. The polysiloxane moiety may be of the formula EQU --O--R--Si(CH.sub.3).sub.2 O].sub.b' R--O--
where b' is 6-35, and R is a linear or branched C.sub.1 -C.sub.12 alkylene. Polysiloxane polyols, e.g., hydroxy-terminated diorganosiloxanes, and siloxanes with reactive hydroxyl groups bonded to at least two of its silicon atoms, are disclosed as useful precursors for the siloxane moiety of the molecule; the diurethane moiety of the molecule may be formed from polyisocyanates such as isophorone diisocyanate (IPDI); and the acrylate portion of the compound may be derived from hydroxy (meth)acrylates or hydroxyalkyl (meth)acrylates. A radiation addition-polymerizable mono- or poly-functional diluent monomer, e.g., methyl methacrylate or isobornyl methacrylate, may be added to the oligomer product, to lower the viscosity of the composition and insure requisite crosslink density in plastic articles formed therefrom.
European Patent Application No. 127,321 of S. W. Bany, et al describes compositions for forming contact lenses, comprising organopolysiloxane monourethane acrylate monomers of 500-20,000 molecular weight, which are copolymerized with ethylenically unsaturated monomers and have terminal acryl-or methacryloyloxyalkylcarbamoyloxyalkyl groups of the formula ##STR1## wherein R.sup.2 is hydrogen or methyl, c is 2-6, and d is 1-12. Such organopolysiloxane urethane (meth)acrylates may be formed by reacting the corresponding hydroxyalkyl-terminated organopolysiloxanes with isocyanato alkyl (meth)acrylates; the hydroxyalkyl-terminated organopolysiloxanes in turn may be prepared by platinum catalyzed reaction of the corresponding silicon hydride-terminated polysiloxane with "an hydroxy-group-protected .omega.-alkenyl alcohol forming an organopolysiloxane having protected terminal hydroxy groups that on removal yield the desired organopolysiloxane having terminal hydroxyalkyl groups" (page 8, lines 4-7). An illustrative synthesis is shown at page 8, lines 11-40 of the application, as including the platinum-catalyzed reaction of an Si-H terminated dimethylsiloxane with propenyloxytrimethylsilane to yield the corresponding polydimethylsiloxane with trimethylsiloxypropyl end groups, which then is acid catalyzed in aqueous medium to form the corresponding hydroxypropyl polydimethylsiloxane for reaction with isocyanatoethyl methacrylate to form the product bis(urethane methacrylate). The application discloses the preparation of the silicon hydride-terminated polydimethylsiloxane starting material for this synthesis, with molecular weights of 1650 and 2090, by reaction of octamethylcyclotetrasiloxane and tetramethyldisiloxane in sulfuric acid medium.